Air-filled porosity and permeability relationships during solid-state fermentation

An experimental apparatus was constructed to measure the structural parameters of organic porous media, i.,e. mechanical strength, air-filled porosity, air permeability, and the Ergun particle size. These parameters are critical to the engineering of aerobic bioconversion systems and were measured for a straw--manure mixture before and after 13 days of in-vessel composting. Porosity was measured using air pycnometry at four (day 0) and five (day 13) moisture levels, with each moisture level tested at a range of different densities. Tested wet bulk densities varied with moisture level, but dry bulk densities generally ranged from 100 to 200 kg m(-3). At each moisture/density combination, pressure drop was measured at airflow rates ranging from 0.001 to 0.05 m sec(-1), representing the range of airflow rates found in both intensive and extensive composting. Measured air-filled porosities were accurately predicted from measurements of bulk density, moisture, and organic matter content. Reductions in air-filled porosity at increasing moisture content were accompanied by an increase in permeability, apparently due to aggregations of fines. This aggregation was quantified by calculating an effective particle size from the Ergun permeability relationship, which increased from 0.0002 m at 50% moisture to 0.0021 m at 79% moisture. The range of airflow velocities reported in composting systems requires consideration of the second-order drag force term, particularly at velocities approaching 0.05 m s(-1) for the higher moisture treatments tested. Calculated permeabilities for the matrix ranged from 10(-10) to 10(-7) m2, varying with both air-filled porosity and moisture. Mechanical strength characterization provided a means to predict the effects of compaction on air-filled porosity and permeability of porous media beds. The results of this investigation extend porous media theory to the organic matrices common in solid-state fermentations and help build a framework for quantitative and mechanistic engineering design.     

Respirometric screening of several types of manure and mixtures intended for composting

The viability of mixtures from manure and agricultural wastes as composting sources were systematically studied using a physicochemical and biological characterization. The combination of different parameters such as C:N ratio, free air space (FAS) and moisture content can help in the formulation of the mixtures. Nevertheless, the composting process may be challenging, particularly at industrial scales. The results of this study suggest that if the respirometric potential is known, it is possible to predict the behaviour of a full scale composting process. Respiration indices can be used as a tool for determining the suitability of composting as applied to manure and complementary wastes. Accordingly, manure and agricultural wastes with a high potential for composting and some proposed mixtures have been characterized in terms of respiration activity. Specifically, the potential of samples to be composted has been determined by means of the oxygen uptake rate (OUR) and the dynamic respirometric index (DRI). During this study, four of these mixtures were composted at full scale in a system consisting of a confined pile with forced aeration. The biological activity was monitored by means of the oxygen uptake rate inside the material (OURinsitu). This new parameter represents the real activity of the process. The comparison between the potential respirometric activities at laboratory scale with the in situ respirometric activity observed at full scale may be a useful tool in the design and optimization of composting systems for manure and other organic agricultural wastes.     

Influence of straw types and nitrogen sources on mushroom composting emissions and compost productivity

The effects of different straw types and organic and inorganic nitrogen (N) sources on the chemical composition and odor concentration (OC) of mushroom composting emissions, compost parameters, and mushroom yield were examined using bench-scale and large-scale (windrows and aerated tunnels) composting systems. There were close correlations between the butanol or combined H₂S+dimethyl sulfide (DMS) concentration and OC of air samples taken from different composting ingredients (r=0.83 and 0.76–0.87, P<0.01, for log_e-transformed data). Differences in N availability, in terms of NH₃ and N losses during composting, were found between different N sources. Materials in which the N was less available (chipboard and digester wastes, cocoa shells, ammonium sulfate) produced lower mushroom yields than materials in which the N was more readily available (poultry manure, urea, brewers' grains, hop and molasses wastes, cocoa meal). Replacement of poultry manure with the other N sources at 50–100% or wheat straw with rape, bean, or linseed straw in aerated tunnel or windrow composts reduced the OC and emissions of odorous sulfur-containing compounds, but also reduced yield. Urea and cocoa meal may be suitable for “low odor” prewetting of straw, with addition of poultry manure immediately before aerated tunnel composting. Rape straw in compost reduces the formation of anaerobic zones and resulting odorous emissions, since it maintains its structure and porosity better than wheat straw. Journal of Industrial Microbiology & Biotechnology (2002) 29, 99–110 doi:10.1038/sj.jim.7000292 Received 08 January 2002/ Accepted in revised form 20 June 2002     

Continuous thermophilic composting (CTC) for rapid biodegradation and maturation of organic municipal solid waste

Fewer and fewer municipal solid wastes are treated by composting in China because of the disadvantages of enormous investment, long processing cycle and unstable products in a conventional composting treatment. In this study, a continuous thermophilic composting (CTC) method, only a thermophilic phase within the process, has been applied to four bench-scale composting runs, and further compared with a conventional composting run by assessing the indexes of pH, total organic carbon (TOC), total Kjeldahl nitrogen (TKN), C/N ratio, germination index (GI), specific oxygen uptake rate (SOUR), dissolved organic carbon (DOC) and dehydrogenase activity. After composting for 14 days, 16 days, 18 days and 19 days in the four CTC runs, respectively, mature compost products were obtained, with quality similar to or better than which had been stabilized for 28 days in run A. The products from the CTC runs also showed favorable stability in room temperature environment after the short-term composting at high temperature. The study suggested CTC as a novel method for rapid degradation and maturation of organic municipal solid wastes.     

Determination of aeration rate and kinetics of composting some agricultural wastes

This study aimed to determine the aeration rate and its kinetics in aerobic composting of agricultural wastes. For this aim compost materials were prepared by mixing grass trimmings, tomato, pepper, and eggplant wastes. Four vertical forced aeration type reactors and one vertical natural convection type reactor were manufactured to apply four different aeration rates. CO2 rate and temperature changes were recorded in three different places in the reactors. Moisture content, pH and organic material rate were recorded each day. While process-monitoring parameters (CO2, temperature, pH, moisture content) were used for interpretation of the process, organic material degradation was used for interpretation of the process success. The seven different kinetic models were applied for modeling decomposition rate to the experimental values. According to the results, four of these models were found applicable to this study. These models were analyzed with some statistical methods as root mean square error (RMSE), chi-square (chi2), and modeling efficiency (EF). According to the statistical results of these models, the best model was found as: [Formula: see text] where kT is the rate of decomposition (g VS/g VS day); T the process temperature (degrees C); Mc the daily moisture content (%wb); C the daily CO2 rate in composting reactor (%) and a, b, c, d are constants. According to the results, the highest organic matter degradation and temperature value were obtained at the aeration rate of 0.4 l air min(-1)kg(om)(-1). Thus, it could be applied to this mixed materials composting process.     

绿化废弃物资源化利用促进绿色农业循环发展

绿化废弃物资源化循环利用对树立环保理念,引领人们积极参与绿化垃圾收集、分类,提高农业绿色可持续发展和生态保护及实施"沃土工程"具有重要意义。该研究利用校园绿化产生的绿化废弃物,采用条垛发酵技术进行堆肥发酵,制成有机覆盖物和土壤改良剂,对土壤改良剂物理性质(容重、总孔隙度、持水孔隙、p H值、EC值等指标)和营养含量及土壤改良剂浸提液发芽率进行了测定。随后将土壤改良剂应用到校园试验田中进行土壤改良,并通过测定土壤改良前后大田土壤物理性质和营养含量及凤仙花和油菜生长状况对土壤改良剂进行效果评估;同时将有机覆盖物分别应用在校园树穴、校园裸土表面和花坛中进行示范,调查处理样方四个季节杂草含量及杂草抑制率进行有机覆盖物效果评价。结果表明:油菜在改良土壤中长势优于对照,土壤改良剂对土壤板结和土壤可耕性具有较好的改良效果。生长在土壤改良剂基质中的凤仙花长势不如购买基质,表明土壤改良剂不适合直接作为营养栽培基质;有机覆盖物应用在校园树穴、校园裸土表面和花坛中,对杂草具有显著抑制作用并具有很好的景观效果。此外,还对堆肥关键技术和目前绿化废弃物资源化存在的问题进行了讨论。     

烟草废弃物在堆肥领域的研究进展

在烟草生产及加工过程中,通常会产生大量的烟草废弃物,如何有效利用这些废弃物以避免环境污染和资源浪费,已成为烟草行业亟需解决的问解。研究发现,烟草废弃物堆肥化处理是规模化利用废弃资源的有效途径之一,对烟草农业的绿色、低碳、循环、可持续发展具有重要意义。从有机肥堆肥制备技术、肥效研究等方面进行了系统综述,从整体上展示了烟草废弃物堆肥技术的发展现状,以期为国内烟草废弃物源堆肥未来技术的研发及产业化提供一定的参考。通过分析发现,在堆肥制备技术方面,主要有微生物菌剂添加技术、共堆肥技术和烟草材料预处理技术3种,此外还衍生出液态有机肥和厌氧发酵联产有机肥技术;在堆肥肥效研究方面,烟草废弃物堆肥可明显改善土壤的物性参数、化学参数以及生物学参数,显著钝化土壤重金属元素,进而提高作物的产量或品质,其中堆肥与化学肥料配施的效果相对较好;堆肥的多功能化是未来堆肥创新利用的重要途径。     

Emission of methane and carbon dioxide and earthworm survival during composting of pharmaceutical sludge and spent mycelia

Emissions of methane (CH4) and carbon dioxide (CO2) from spent mycelia of the mold Penicilium notatum and sludge from the effluent treatment facility (ETPS) of a pharmaceutical industry were estimated twice during a two-week composting before vermicomposting. These wastes are dumped in landfills or sometimes used in agricultural fields and no reports are available on their greenhouse gas producing potentials. The solid wastes contained appreciable organic carbon and nitrogen while very high Fe, Mn and Zn were found in ETPS only. Pure wastes did not support germination of Vigna radiata L. while mixing soil with ETPS and spent mycelia at the ratios of 12:1 and 14:1 led to 80% and 50% germination, respectively. The wastes were mixed with cowdung at the ratios of 1:1, 1:3 and 3:1 for composting. Carbon dioxide emissions were always significantly higher than CH4 emissions from all the treatments due to prevalence of aerobic condition during composting. From some treatments, CH4 emissions increased with time, indicating increasing activity of anaerobic bacteria in the waste mixtures. Methane emissions ranged from 21.6 to 231.7 microg m(-2) day(-1) while CO2 emissions were greater than thousand times at 39.8-894.8 mg m(-2) day(-1). The amount of C emitted as CH4-C and CO2-C from ranged from 0.007% to 0.081% of total C composted. Cowdung emitted highest CH4 followed by spent mycelia and ETPS while ETPS emitted more CO2 than spent mycelia but lesser than cowdung. Global warming potential of emitted CH4 was found to be in the range of 10.6-27.7 mg-CO2-equivalent on a 20-year time horizon. The results suggest that pharmaceutical wastes can be an important source of CH4 and CO2 during composting or any other stockpiling under suitable moisture conditions. The waste mixtures were found not suitable for vermicomposting after two weeks composting and earthworms did not survive long in the mixtures.     

堆肥微生物学研究现状与发展前景

综述了有机固体废弃物堆肥微生物学的研究方法的最新进展,以及堆肥过程中微生物的研究现状,提出了堆肥微生物学研究存在的主要问题和发展趋势。     

Transformation of rock phosphate during composting and the effect of humic acid

Summary Phosphorus from Mussoorie rock phosphate (MRP) was solubilized and transformed into available forms when MRP was incorporated during composting of organic wastes. Clusterbean and redgram utilized phosphorus efficiently from the phosphorus enriched compost containing 3.1% P when added in the soil of pH 7.6 to 7.8. The solubilization of phosphorus during composting has been attributed to the formation of humic substances.     

Olive mill waste composting: A review

Olive mill wastes exacerbate environmental problems in Mediterranean countries. These wastes are highly phytotoxic and contain phenolic compounds, lipids and organic acids. They also contain high percentages of organic matter and a vast range of plant nutrients that could be reused as fertilizers for sustainable agricultural practices. In this paper, recent research on composting wastes of 2-phase and 3-phase olive mills is reviewed, concentrating on factors affecting composting such as bulking agents, aeration strategy, physicochemical characteristics (duration of the thermophilic phase, moisture content, organic matter, volatile solids, total organic carbon, water soluble carbon, total nitrogen, total phosphorus, potassium, C/N ratio, phenols and the humification process), and phytotoxicity. The review highlights the effects of composting operational factors (bulking agent, additives, and aeration strategy) on the physicochemical characteristics of the final compost, and the production of a good quality soil amender or fertilizer.     

Use of olive mill wastewater compost for crop production

Vast amounts of olive mill wastewaters (OMW) are produced in Mediterranean countries, where their treatment and disposal are becoming a serious environmental problem. Increasing attention has been paid to discovering a use for OMW and a wide range of technological treatments are available nowadays for reducing their pollutant effects and for their transformation into valuable products, the most suitable procedures being found to involve recycling rather than the detoxication of these wastes. Direct application of OMW to soil has been considered as an inexpensive method of disposal and recovery of their mineral and organic components but, because of their organic acid and phenol contents, OMW are also a source of pollution. By using composting technologies, it is possible to transform either fresh OMW or sludge from pond-stored OMW mixed with appropriate plant waste waterials (carriers) into organic fertilizers (composts) with no phytotoxicity to improve soil fertility and plant production, the process involving the microbial degradation of the polluting load of the wastes. Results of field and pot experiments using OMW-composts to cultivate horticultural and other crops have shown that yields obtained with organic fertilization are similar, and sometimes higher, to those obtained with a balanced mineral fertilizer. A comparison between the macro and micronutrient contents of plants cultivated with organic or mineral fertilizers did not generally reveal important differences. However, the cases of iron and manganese are worth mentioning as their bio-availability may be linked to the soil humic complexes originated by the OMW organic fertilizers.     

微生物在有机固废堆肥中的作用与应用

好氧堆肥是实现有机固体废弃物资源化利用的主流处理方式.堆肥腐熟是一个由微生物主导的生理生化过程,堆料通过微生物发酵实现矿质化、腐殖化和无害化,转变成腐熟的有机肥.传统的好氧堆肥存在发酵周期长、养分损失、恶臭及温室气体排放等不足.在堆肥过程中添加微生物是弥补传统好氧堆肥缺陷、提高堆肥品质和功效的有效方法.近年来,国内外在...     

Composting of spent mushroom compost, carnation wastes, chicken and cattle manures

This study has purposed to determine the optimum mixture ratio of used mushroom compost, chicken manure, cattle manure and carnation waste for composting. For this purpose, these materials have been mixed in seven various ratios (R1-R7) and composted in the experimental composting reactors. The highest dry material losses and temperature values have been obtained by the R4 which contains 50% carnation waste, 25% chicken manure and 25% spent mushroom compost. Beside R4, mixtures of R2, R5 and R6 have also provided high process temperature and dry material loss values. The lowest dry material loss and temperature values have been obtained in the R7 which contains only carnation wastes. In the study, it has also seen that FAS (free air space) parameter is effective on the process and must be in the interval of 24-32%.     

农业有机废弃物中挥发性成分的过程控制

随着养殖业的发展禽畜废弃物已经成为有机废弃物的主要来源之一,并产生了很多恶臭气体,对环境造成了严重污染。论述了恶臭气体的发生、危害及国内外物理、化学、生化和生物法过程控制的研究进展,并在此基础上提出了微生物在禽畜废弃物恶臭气体控制中的问题和研究展望。     

Microbiology of nitrogen cycle in animal manure compost

Composting is the major technology in the treatment of animal manure and is a source of nitrous oxide, a greenhouse gas. Although the microbiological processes of both nitrification and denitrification are involved in composting, the key players in these pathways have not been well identified. Recent molecular microbiological methodologies have revealed the presence of dominant Bacillus species in the degradation of organic material or betaproteobacterial ammonia‐oxidizing bacteria on nitrification on the surface, and have also revealed the mechanism of nitrous oxide emission in this complicated process to some extent. Some bacteria, archaea or fungi still would be considered potential key players, and the contribution of some pathways, such as nitrifier denitrification or heterotrophic nitrification, might be involved in composting. This review article discusses these potential microbial players in nitrification–denitrification within the composting pile and highlights the relevant unknowns through recent activities that focus on the nitrogen cycle within the animal manure composting process.     

Composting of municipal solid waste

This paper reviews the literature on the composting process, which is one of the technological options for the processing of municipal solid wastes (MSWs). The process assumes a great significance, particularly from the point of its economic viability, capability for recycling of nutrients and waste minimization with minimum environmental problems. A number of studies on various aspects of the composting process, including process control and monitoring parameters such as temperature, pH, moisture content, aeration, and porosity are reviewed. Salient observations on microbial properties of composting are described and details of vermicomposting, as well as a detailed analysis of patents on composting of MSW, are presented.     

Monitoring of green waste composting process based on redox potential

Among compostable matrices, green wastes represent a significant fraction which can be used as an amendment after composting. Several indicators, e.g. C(HA)/C(FA) or C/N ratios give information on evolution of the organic matrix during composting. However, measurement of these parameters is complex and requires laboratory conditions. The aim of this study was to propose on site easy-to-measure parameters to monitor composting process, such as redox potential (Eh), related to complex indices such as C(HA)/C(FA), C/N, A(210 nm)/A(280 nm), NH(4)(+)/NO(3)(-) ratios, and total organic matter (OM). Windrows were consisting in a mixture of green wastes such as palm, olive, cypress, pine, mimosa, and bay residues. By using covariance analysis, an opposite correlation between Eh and C(HA)/C(FA) ratio was found. Linear regression of this parameter with Eh was chosen to monitor the composting process. Therefore, Eh can be used to monitor green wastes composting.     

蚯蚓堆制处理对农业有机废弃物的化学及生物学影响的主成分分析

在实验室可控条件下,以碳氮比28.7∶1的农业有机废弃物（牛粪和稻秆）为赤子爱胜蚓(Eisenia foetida)的培养基质,研究蚯蚓的堆制作用对有机物料的化学及生物学特性的影响.结果表明： 蚯蚓堆制处理30 d后,基质pH值、碳氮比显著降低,全磷显著升高,而全氮、碱解氮、可溶性碳、速效磷、微生物生物量碳、呼吸速率和微生物熵分别提高8.5%、2.6%、18%、63%、212%、44%和300%,有机质、呼吸熵分别降低5.0%和21.9%.蚯蚓堆制处理后物料具有较高的转化酶、酸性和碱性磷酸酶活性,较低的过氧化氢酶和脲酶活性.多元数据分析结果显示,自然堆制和蚯蚓堆制处理物料的化学和生物学特性均呈现显著的差异性.蚯蚓堆制处理优于自然堆制处理,可以明显改善有机物料的化学、生物学性质,是一种高效率处理农业有机废弃物的技术.